Alcanivorax is a globally distributed genus of oil-degrading bacteria. They are extreme halophiles and show a highly restricted range of growth substrates, primarily aliphatic hydrocarbons and a few organic acids. Although Alcanivorax is normally a minor component of unpolluted waters, they will increase to high numbers in oil-polluted waters, where it can comprise >80 % of the hydrocarbon-degrading bacterial community.

However, there is a question of why Alcanivorax is found throughout the worldaa??a??s oceans, when much of the ocean is not polluted with oil. Iits natural reservoir may be in association with hydrocarbon-rich phytoplankton, such as dinoflagellates. During a study of bacteria associated with marine dinoflagellates, we isolated Alcanivorax sp. from three strains of the toxic dinoflagellate Gymnodinium catenatum from Korea, Australia and New Zealand and Dinophysis acuminata from Scotland. This points to Alcanivorax as a potentially important component of the marine carbon cycle in both pristine and polluted waters.

It is also one of only a few bacterial taxa that can stimulate dinoflagellate growth. In this regard, the parallels between Alcanivorax and aa??E?Marinobacter algicolaaa??a?? are striking. Notably, the highly similar (aa??Y99.4 % 16S rDNA similarity) type strain Alcanivorax borkumensis SK2 (Y12579) does not support dinoflagellate growth.